Schedule I Parent Only Balance Sheets, Statements Of Earnings And Cash Flows (Balance Sheets) (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
ASSETS
Cash and cash equivalents	$ 333,761	$ 11,054	$ 119,311	$ 5,760
Prepaid expenses and other current assets	35,944	42,275
Other assets, net	74,748	69,105
Total assets	1,668,190	1,262,959
LIABILITIES AND PARTNERS' CAPITAL (DEFICIT)
Current portion of long-term debt	859,095	631,756
Other current liabilities	167,466	138,237
Long-term debt	1,646,396	1,457,004
Partners' capital (deficit)
Common unitholders	(1,126,452)	(1,046,245)
General partner unitholder	(71,287)	(70,476)
Accumulated other comprehensive income (loss)	(2,303)	(14,512)
Total Ferrellgas Partners, L.P. partners' deficit	(1,200,042)	(1,131,233)
Total liabilities and partners' capital (deficit)	$ 1,668,190	$ 1,262,959
Common unitholders, units outstanding	97,152,665	97,152,665
General partner unitholder, units outstanding	989,926	989,926
Parent Company [Member]
ASSETS
Cash and cash equivalents	$ 6	$ 8	3	59
Prepaid expenses and other current assets	22	57
Total assets	28	65
LIABILITIES AND PARTNERS' CAPITAL (DEFICIT)
Current portion of long-term debt	357,000	354,727
Other current liabilities	19,305	3,873
Investment in Ferrellgas, L.P.	823,765	772,698
Partners' capital (deficit)
Common unitholders	(1,126,452)	(1,046,245)
General partner unitholder	(71,287)	(70,476)
Accumulated other comprehensive income (loss)	(2,303)	(14,512)
Total Ferrellgas Partners, L.P. partners' deficit	(1,200,042)	(1,131,233)
Total liabilities and partners' capital (deficit)	$ 28	$ 65
Common unitholders, units outstanding	97,152,665	97,152,665
General partner unitholder, units outstanding	989,926	989,926
Parent Company [Member] | Reportable Legal Entities [Member]
ASSETS
Cash and cash equivalents	$ 332,244	$ 11,045	$ 119,133	$ 5,327
Prepaid expenses and other current assets	35,897	42,158
Investment in Ferrellgas, L.P.	37,662	52,999
Other assets, net	72,137	65,447
Total assets	1,682,098	1,195,017
LIABILITIES AND PARTNERS' CAPITAL (DEFICIT)
Current portion of long-term debt	502,095	277,029
Other current liabilities	162,097	128,666
Long-term debt	1,646,396	1,457,004
Partners' capital (deficit)
Accumulated other comprehensive income (loss)	(2,313)	(14,647)
Total Ferrellgas Partners, L.P. partners' deficit	(831,991)	(780,403)
Total liabilities and partners' capital (deficit)	$ 1,682,098	$ 1,195,017